Surgical treatment for flat type colorectal early cancer

Three hundred and eighty three early colorectal cancers which are limited within the mucosa (m) and submucosa (sm) were analyzed clinically and pathologically. They were classified macroscopically to protruded type and flat type. Protruded type cancers were subclassified to Ip pedunculated (m: 84, sm: 38), Isp subpedunculated (m: 49, sm: 51), Is sessile (m: 26, sm: 49) and flat type cancers were also subclassified to IIa flat-elevated (m: 27, sm25), IIa + IIc flatelevated with depression (m: 4, sm: 26) and IIc slightly depressed (m: 0, sm: 2). It was difficult to diagnose exactly whether the polyps was m cancer or sm cancer from the macroscopic findings. As for patients who received curative resection, the lymph node metastasis rate of flat type sm cancer were 13.6% in IIa and 20.0% in IIa + IIc while in protruded type sm cancer it was 3.4% in Ip, 7.1% in Isp and 9.3% in Is. In all patients, the rate of lymph node metastasis and/or recurrent disease in patients with flat type cancer was 16.0% in IIa and 19.2% in IIa + IIc, while in patients with protruded type cancer it was 5.3% in Ip, 9.8% in Isp and 8.2% in Is. Since flat type sm cancer is likely to have lymph nodes metastasis and postoperative recurrence, it should be treated by curative resection.